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Summary
Palynostratigraphy is one of the primary methods employed to date and correlate strata on the Northwest Shelf. In this setting dinocysts provide the highest resolution for the Mesozoic, particularly for the Middle–Upper Jurassic interval. This period is characterized by a global-scale dinoflagellate radiation, which is reflected, in the Bathonian–Kimmeridigian strata of the Northwest Shelf by the highly diverse W. indotata–D. swanense assemblages
Transmitted light and scanning electron microscopy were used to document the palynological assemblages of 235 palynological strew slides prepared from conventional and sidewall cores from wells in the Bonaparte and Northern Carnarvon. Previously undescribed species of dinocyst were identified, and their geographic and stratigraphic ranges were documented. The data from all wells was then integrated to i) characterize the morphological variations of species across different basins, ii) identify common biostratigraphic events and iii) produce an updated regional biostratigraphic scheme.
Eleven new species of dinocyst and one species of acritarch with stratigraphic values have been formally described as a result of this work. An additional fourteen species, and two dinocyst genera were identified, of which four have been identified as potential biostratigraphic markers.
Most of the new species present a consistent stratigraphic distribution in both the Bonaparte and the Northern Carnarvon basins. These new markers increase the resolution of the regional biostratigraphic scheme.
The events observed in the Bonaparte Basin, increase the accuracy of well to well correlations and further characterise the evolution of the local area during the Bathonian–Kimmeridgian interval. Further investigation is likely to yield additional, significant biostratigraphic events.